Rock boring machine with swinging hammers and steering

ABSTRACT

A rock boring machine comprising a mobile chassis supporting a forwardly projecting rotatable shaft carrying at its forward end a cutting head having at least one independently rotatable rotor with hammers free swinging between end stops pivoted thereto and means for angularly varying the position of the cutting head relative to the chassis while maintaining a rotor cutting path adapted to form a track for the chassis. The cutting head is preferably angularly adjustable in both horizontal and vertical planes by having the machine mounted on a bed plate supported by the chassis to allow universal movement between the bed plate and chassis.

[ July 31, 1973 United States Patent 1191 Taylor ROCK BORING MACHINE WITH SWINGING HAMMERS AND STEERING [75] Inventor: Richard Francis Taylor,

Johannesburg, Transvaal Province, South Africa [73] Assignee: Anglo-Transvaal Consolidated Primary Purser Investment Company Limited, AttorneyStevens, Davis, Miller & Mosher Johannesburg, South Africa July 26, 1971 [S 7] ABSTRACT A rock boring machine comprising a mobile chassis supporting a forwardly projecting rotatable shaft carry- [22] Filed:

21 Appl. No.: 166,022

ing at its forward end a cutting head having at least one independently rotatable rotor with hammers free [30] Foreign Application Priority Data July 31, 1970 South 705310 Swinging between end Stops pivoted thereto and means for angularly varying the position of the cutting head relative to the chassis while maintaining a rotor cutting path adapted to form a track for the chassis. The cutting head is preferably angularly adjustable in both horizontal and vertical planes by having the machine 64 4 BNSQ 93 ,3 9 .67 2 5 3, 2 l wn W U 3 9 2 B 2 mm m 9 u 9 U U 2 m m; unuz "uu6 WWWS "WW8 mm 6 nm m8 mum 6 I 8 mu w I hf o SL6 i U.mF N 555 mounted on a bed plate supported by the chassis to allow universal movement between the bed plate and chassis.

[56] References Cited UNITED STATES PATENTS 3,061,288 10/1962 299/31 8 Claims, 5 Drawing Figures PATENIE JUL 3 1 I975 SHEET 1 OF 2 PATENTEUJULBHBR sum 2 [IF 2 ROCK BORING MACHINE WITH SWINGING IIAMMERS AND STEERING This invention relates to rock boring machines for making tunnels and more particulary to such machines which have a frontal cutting head rotated by a main shaft and which are mounted on mobile chassis.

The object of the present invention is to provide a machine which can negotiate the types of bends which are often required in mining and civil engineering operations.

According to this invention there is provided a rock boring machine comprising a mobile chassis supporting a forwardly projecting rotatable shaft carrying at its forward end a cutting head having at least one independently rotatable rotor with hammers free-swinging between end stops pivoted thereto, and means for angularly varying the position of the cutting head relative to the chassis while maintaining a rotor cutting path adapted to form a track for the chassis.

Further features of this invention provide for the cutting head to be angularly variable in both vertical and horizontal planes, for the chassis to be supported on steerable wheels and/or for the shaft to be carried on a bed plate pivotally mounted on the front of the chassis to have universal movement relative to the chassis.

A preferred embodiment of the invention will be described below by way of example, reference being made to the accompanying drawings in which:

FIG. I is a part-sectional side elevation of a rock boring machine;

FIG. 2 is an outline plan of the machine in a straight tunnel in which the rotor is shown in section taken along line HH of FIG. 1.

FIG. 3 is a part-sectional end elevation of the machine on line A-A;

FIG. 4 is a part-sectional end elevation of the machine on line 8-8; and

FIG. 5 is an outline plan of the machine negotiating a bend of a radius, measured to the center line of the tunnel, equal to four tunnel diameters.

In this embodiment of the invention a rock boring machine includes a wheeled chassis 1 (shown by chain dotted lines) carrying a bed plate 2 (shown by dotted lines). The bed plate 2 is pivotally mounted on the front end of the chassis l in such a manner enabling the bed plate 2 to have universal movement relative to the chassis 1.

The bed plate 2 supports on suitable bearings 3 a main shaft 4 extending beyond the front of the chassis I where a cutting head 5 is carried by said shaft 4. The main shaft 4 and cutting head are adapted to turn relatively slowly and are powered by an hydraulic motor located on the bed plate and through a chain transmission 6.

The cutting head 5 comprises a frame 7 rotatably supporting two cutting rotors 8. The rotors 8 each have a plurality of free-swinging hammers 9 on the periphery, which hammers are adapted to swing outwardly between end stops 35 under the influence of centrifugal force.

The preferred design of a rotor is such that when the hammers strike the rock, no shock load is thrown back onto the hammer pivot. To obtain this desired effect each hammer is pivotally secured to the rotor at one end. The center of gravity of the hammer is eccentric to the pivot and allows a combination of both radial and rotational movement of the striking tip relative to the axis of rotation of the rotor. The design characteristics of the hammer are achieved by ensuring that the distance of the striking tip from the pivot is equal to the (radius of gyration) divided by the distance between the pivot and the center of gravity.'A detailed disclosure of such a hammer is given in our U.S. Pat. No. 3,695,724.

It is also desirable that all the energy given up by the hammer in striking the tool is restored to the hammer by the centrifugal force applied thereto during the remaining portion of the revolution of the rotor in order to bring the hammer back into thestriking position, just at the correct time to strike the rock. This characteristic can seldom be attained and from a practical point of view it is necessary to use shock absorbers to limit the swing of the hammers in both directions.

The rotors 8 are driven by an hydraulic motor 10 independently of the motor powering the main shaft 4.

Pressurised fluid for the motor 10 for the rotors 8 is fed through suitable passages in the main shaft 4. Hydraulic slip rings 11 are used to permit flow of fluid through the shaft 4. In a similar manner any necessary control signal transmitting means for the rotors 8 are passed through passages in the main shaft 4 and in the case of electrical conductors are collected by a bank of electrical slip rings 12.

The control console for the machine is also located on the bed plate. The console includes monitoring and control means for the power driven units in the machine and for an electrically driven hydraulic power pack for these units. The power pack will also preferably be located on the bed plate.

A wheel 13 adapted to interact against the ceiling of the excavated tunnel is vertically adjustable by means of a jack 14. The jack l4 and a supporting arm 15 for the wheel are pivotally mounted on the bed plate 2. The wheel 13 is located at the rear of the machine to counteract any tendency of the cutting head to tip downwardly.

Secured to the shaft in front of the chassis l, but behind the cutting head 5, is a lifting and dust prevention shield 14 shown diagrammatically in section. The shield 14 forms a reasonably dustproof seal between thecutting head 5 and the remainder of the machine and has a number of lifting scoops 15, mounted in such a manner as to pick up broken rock as the shield slowly revolves with the shaft 4. The scoops l5 guide the rock to a passage (not shown) through the shield 14, said passage being located to enable the broken rock to be discharged onto a swivel conveyor 16 supported by the bedplate 2. The conveyor 16 is used to transport the broken rock to the rear of the machine, where it is de-.

posited on suitable removing means for broken rock.

In order that roughness in the sides of the tunnel and also debris which has not been picked up by the scoops 15 does not interfere with the shield, a clearance must exist between the shield 14 and the sides of the tunnel. This clearance can be sealed by a seal 17 of flexible material such as fabric reinforced rubber strips.

A suitably sealed cowl 18 connected to a suction fan is arranged around the junction of the shaft 4 and shield 14 to enable dust laden air from the working rockface to be sucked through the shield and disposed of safely.

The bed plate 2 is pivotally mounted at the front of the chassis on a post 20 having oppositely disposed trunnions 21 (shown by solid lines). The bed plate 2 is pivotally connected to the horizontal trunnions 21, whereas the post 20 extends into a bearing surface in the chassis 1.

Controlled limited lateral movement of the bed plate and equipment carried thereby can be obtained by enclosing the ends of trunnions 21 in cylinders 22. The trunnion bearings will be suitably sealed and by introducing fluid under pressure into one or other of the cylinders the lateral movement can be obtained. The bearing for the post and the post itself may also be optionally converted to an hydraulic cylinder capable of lifting the post 20 and consequently the bed plate 2.

Movement of the bed plate and consequently of the cutting head relative to the chassis can be achieved in several ways. In another instance, the connecting bar between the two trunnions 21 may have a central hole therethrough instead of the post 20, said hole being adapted to receive a pin made integral with the chassis. Rubber bushes may be used as bearing surfaces which bushes will also accommodate limited movement between the mating parts.

When negotiating curves, it is necessary to ensure that no part of the machine fouls the side of the tunnel. Provided that the bed plate 2 is shaped correctly and is not too long with respect to the diameter of the tunnel, the side of the tunnel will not be fouled. A more critical condition is illustrated in plan in FIG. 5 where the machine is negotiating a curve of radius equal to four times the tunnel diameter. It is necessary for the wheeled chassis 1 to track along the center line 24 of the tunnel; at the same time, it is necessary for the shield to fit in the tunnel reasonably well without fouling and also for the cutting rotors 8 to ream out the tunnel on the correct centre line.

In FIG. 2 the plane indicated by the line CC is the plane in which the vertical axis of the post with trunnions lies. This plane is at right angles to the centre line 24 of the tunnel. The planes DD and EE similarly are planes in which the front and rear wheel axes lie. FF is the plane bisecting the seal 17 and the plane 06 is that at which the final diameter of the tunnel is formed. The planes referred to are chosen to show the situation of the components when the planes are at right angles to the center line of the tunnel.

Ideally, if the distance measured on the center line of the tunnel between planes DD and EE is equal to the distance between planes FF and GG and if the wheels 25 of the chassis track on the horizontal diameter of the tunnel and if the plane CC lies midway between planes DD and FF then the machine will be able to negotiate bends of any constant radius without the shield 14 fouling the sides of the tunnel.

In the preferred design, however, the wheels 25 do not track on the horizontal diameter of the tunnel, furthermore, the distance between planes DD and EE does not have to equal the distance between planes FF and 66. A further factor is that a normal tunnelling machine has to negotiate curves which vary in their radii as the tunnel progresses. Thus there would be a tendency for a close fitting shield 14 to foul the tunnel sides.

Should the radii to be negotiated be large, it is possible that the tendency of the shield 14 to foul when negotiating bends of changing radii will be so slight, that the margin of flexibility of the seal 17 will not be exceeded and no damage will result. However, should the radii to be negotiated be small, then the controlled lateral movement of the pivot made available by the hydraulic ram effects of cylinders 22 will enable the machine to operate without the shield 14 fouling the tunnel. It is envisaged that radii equal to twice the tunnel diameter can be negotiable with such an arrangement.

The above description applies in a similar manner to means providing movement in the vertical plane, although the vertical radii negotiated will generally be much greater.

Neither of the two axes of rotation of the post 20 and trunnions 21 is required specifically to pass through the axis of shaft 4. In the preferred design it will be seen that one axis does pass through the axis of the shaft 4 (when the cylinders 22 are in the central position) and one does not.

Sequencing of the axial movement of the post 20 and trunnions 21 in correct synchronism with the rotation of the cutting head would enable a wider and/or a higher tunnel to be driven.

The rear end of the bed plate 2 rests on a slide 27 capable of being raised and lowered by means of jacks 28 which press against the chassis l. The slide 27 is guided in its up and down movement by horn guides 29 formed on the chassis l. A ridge 30 can be formed on the slide 27 to enable the bed plate 2 to rock on the slide more effectively.

It will be appreciated that by lifting or lowering the slide 27, the bed plate 2 will be tipped down or up and thus the machine will be capable of negotiating vertical curves.

The rear portion of theslide 27 is formed as an are having a center at the vertical axis of the post 20. On this are shape is formed a curved rack 31 either of gear teeth or roller chain into which a suitable gear or sprocket 32 meshes. The gear or sprocket is operated by geared handle 33 attached to the bed plate 2. It will be understood that by operating the handle the bed plate 2 may be made to pivot about the post 20 and the machine can be made to negotiate horizontal curves. A locking device either separate or inherent in the gear assembly 33 would be required to prevent uncontrolled slewing of the bed plate.

Vertical and horizontal curves may then be negotiated simultaneously.

In an alternate form of the invention, the chassis and consequently the cutting head may be moved relative to the plane through the axes of the wheels to provide the necessary turning of the machine during use.

For this purpose, at least the rear wheels are connected to the chassis by suitably located jacks. Operation of the jacks may then move the chassis, bed plate and head vertically relative to the plane through the axes of the wheels.

Curved tracking in the horizontal plane can'be facilitated by making at least one pair, but preferably all, of the wheels steerable, in addition to one of the forms of the invention described above for this purpose. The wheels will preferably be independently driven through their own hydraulic motors 36.

It will be appreciated that due to the hammering action of the cutting head, little reaction need be provided by the machine to obtain breaking of the rock and what is necessary can readily be provided by the mobile chassis above described.

If greater reaction is necessary, the chassis can be mounted on suitable crawler tracks and steering effected through control of these tracks in known manner.

What I claim as new and desire to secure by Letters Patent is:

l. A rock boring machine comprising a mobile chassis supporting a rotatable shaft, said rotatable shaft forwardly projecting from an area within said chassis to the outside thereof and carrying at its forward end a cutting head having at least one rotatable rotor with hammers free swinging between end stops pivoted thereto, said rotor rotating independently of said shaft, and means for angularly varying the position of the cutting head relative to the chassis while maintaining a rotor cutting path adapted to form a track for the chassis.

2. A rock boring machine as claimed in claim 1 in which the cutting head is angularly variable relative to the chassis in both the vertical and horizontal planes.

3. A rock boring machine as claimed in claim 1 in which the mobile chassis is supported on power driven wheels.

4. A rock boring machine as claimed in claim 3 in which the shaft is carried on a bed plate which is mounted on the chassis to allow universal movement between the bed plate and the chassis.

5. A rock boring machine as claimed in claim 4 in which the universal movement is provided by supporting the bed plate on horizontal trunnions which are themselves carried by a vertical and rotatable post.

6. A rock boring machine as claimed in claim 5 in which the trunnions are movable horizontally relative to the bed plate.

7. A rock boring machine as claimed in claim 3 in which the mobile chassis has steerable wheels separately driven by hydraulic motors.

8. A rock boring machine as claimed in claim 7 in which the chassis carries the rotatable shafton a bed plate and includes hydraulic jacks positioned to enable the shaft to be inclined in a vertical plane relative to the plane through the axes of the supporting wheels. 

1. A rock boring machine comprising a mobile chassis supporting a rotatable shaft, said rotatable shaft forwardly projecting from an area within said chassis to the outside thereof and carrying at its forward end a cutting head having at least one rotatable rotor with hammers free swinging between end stops pivoted thereto, said rotor rotating independently of said shaft, and means for angularly varying the position of the cutting head relative to the chassis while maintaining a rotor cutting path adapted to form a track for the chassis.
 2. A rock boring machine as claimed in claim 1 in which the cutting head is angularly variable relative to the chassis in both the vertical and horizontal planes.
 3. A rock boring machine as claimed in claim 1 in which the mobile chassis is supported on power driven wheels.
 4. A rock boring machine as claimed in claim 3 in which the shaft is carried on a bed plate which is mounted on the chassis to allow universal movement between the bed plate and the chassis.
 5. A rock boring machine as claimed in claim 4 in which the universal movement is proviDed by supporting the bed plate on horizontal trunnions which are themselves carried by a vertical and rotatable post.
 6. A rock boring machine as claimed in claim 5 in which the trunnions are movable horizontally relative to the bed plate.
 7. A rock boring machine as claimed in claim 3 in which the mobile chassis has steerable wheels separately driven by hydraulic motors.
 8. A rock boring machine as claimed in claim 7 in which the chassis carries the rotatable shaft on a bed plate and includes hydraulic jacks positioned to enable the shaft to be inclined in a vertical plane relative to the plane through the axes of the supporting wheels. 